Set vs alphabetical order in Java list

Arent lists ordered collections and is not ordered? So why does this program sort strings alphabetically instead of lists? I understand the repetition of the two

PrintStream out = System.out;

    List<String> set = new ArrayList<String>();
    String s = "ILLUSIONS";

    for(int i = 0; i< s.length(); i++)
    {
        set.add((new Character(s.charAt(i))).toString());

    }
    out.println(set);

Output: Illusions

PrintStream out = System.out;

    Set<String> set = new TreeSet<String>();
    String s = "ILLUSIONS";

    for(int i = 0; i< s.length(); i++)
    {
        set.add((new Character(s.charAt(i))).toString());

    }
    out.println(set);

Output: ilnosu

Solution

The list is "sorted" by element index This means that they retain the order in which elements are inserted Collections (usually) do not retain this order Some exceptions:

>TreeSet is a special set that maintains its elements in a natural "sort" order. > Linkedhashset is a specific set that does preserve the insertion order

If you want to "order" your list, you must do this manually:

Collections.sort(list);

In fact, by "sorting" the list, you will rearrange the indexes of all list elements See collections Related Javadoc on sort()